Field of the Invention
The invention relates to a method and device for configuring functional units in a serial master-slave arrangement and, more particularly, for transferring information or other signals between a plurality of functional units cooperating in a master-slave configuration.
It has become known, heretofore, to connect a master unit and at least one slave unit to a common bus system in order to transfer information. For this purpose, specific circuits are provided in the master unit and the slave units for controlling the transfer of data therebetween. A disadvantage thereof is that the specific circuits are expensive.
Furthermore, it has become known heretofore to provide a master unit with a plurality of serial interfaces to which a respective intelligent slave unit equipped with a computer is connectable. For each additional slave unit to be connected to the master unit, an additional serial interface must be provided which is quite costly in material, as well as generally expensive, and increases the construction volume occupied by the master unit.
The possibility of connecting a plurality of slave units to a serial interface is restricted or limited by the performance of the line-driver components in the master unit. To equip the master unit with specific high-performance driver components likewise increases costs, because such components are not commercially available and consequently require individual development, or because only a limited number of such components are manufactured. Moreover, when a plurality of slave units are connected in parallel with a serial interface of the master unit, each slave unit has to be addressed by means of hardware elements, for example, by providing a number of switches in the slave unit which must be placed in a defined configuration. This procedure does not, however, permit similar slave units to be designed identically with respect to hardware and software, so that they are readily exchangeable, when necessary, for addressing purposes, which would ensure low manufacturing and service costs.
It has also become known, heretofore, to connect a plurality of slave units in series by means of data-transfer lines, one of the slave units located at the end of the serial arrangement being connected to a master unit. The master unit has one serial input/output unit, whereas the slave unit has two serial input/output units. With these constructions, also, the slave units are addressed by hardware elements, i.e., switches or soldering jumpers, having the aforementioned disadvantages.